Control circuit of a full-bridge stage

Abstract

A control circuit for a full-bridge-stage to drive an electric load includes PWM generation circuitry for generating first and second PWM signals so that a difference between duty-cycles of the PWM signals represents an amplitude of a drive current. A logic XOR gate is input with the first and second PWM signals and generates a logic XOR signal. A logic sampling circuit generates a logic driving command of a half-bridge stage, a logic value of which corresponds to a sign of the drive current, by sampling one of the first and second PWM signals based upon active switching edges of the logic XOR signal. A second XOR gate generates a third PWM driving signal of the other half-bridge of the full-bridge stage, a duty-cycle of which corresponds to the amplitude of the drive current.

1. A control circuit for a full-bridge stage to drive an electric load, the control circuit configured to generate a first PWM signal and a second PWM signal so that a difference between duty-cycles of the first and second PWM signals represents an amplitude of a drive current for the electric load, the control circuit also configured to generate a logic driving command of a half-bridge of the full-bridge stage a logic value of which corresponds to a sign of the drive current by combining the first and second PWM signals, the control circuit also configured to generate a third PWM driving signal of the other half-bridge of the full-bridge stage a duty-cycle of which corresponds to the amplitude of the drive current, the control circuit comprising:
 a logic XOR gate configured to be input with the first and second PWM signals and generate therefrom a logic XOR signal; 
 a logic sampling circuit configured to generate the logic driving command by sampling one of the first and second PWM signals based upon active switching edges of the logic XOR signal; and 
 a second XOR gate configured to be input with the logic XOR signal and the logic driving command and generate therefrom the third PWM driving signal. 
 
     
     
       2. The control circuit of  claim 1 , wherein the logic sampling circuit comprises a D-type flip-flop clocked by the active switching edges of the logic XOR signal. 
     
     
       3. The control circuit of  claim 1 , wherein the electric load comprises a voice coil motor. 
     
     
       4. A control circuit for a full-bridge stage to drive an electric load and comprising:
 PWM generation circuitry for generating a first PWM signal and a second PWM signal so that a difference between duty-cycles of the first and second PWM signals represents an amplitude of a drive current for the electric load; 
 a logic XOR gate configured to be input with the first and second PWM signals and generate therefrom a logic XOR signal; 
 a logic sampling circuit configured to generate a logic driving command of a half-bridge of the full-bridge stage, a logic value of which corresponds to a sign of the drive current, by sampling one of the first and second PWM signals based upon active switching edges of the logic XOR signal; and 
 a second XOR gate configured to be input with the logic XOR signal and the logic driving command and generate therefrom a third PWM driving signal of the other half-bridge of the full-bridge stage, a duty-cycle of which corresponds to the amplitude of the drive current. 
 
     
     
       5. The control circuit of  claim 4 , wherein the logic sampling circuit comprises a D-type flip-flop clocked by the active switching edges of the logic XOR signal. 
     
     
       6. The control circuit of  claim 4 , wherein the electric load comprises a voice coil motor. 
     
     
       7. A control circuit for a full-bridge stage to drive an electric load, the control circuit configured to generate a first PWM signal and a second PWM signal so that a difference between duty-cycles of the first and second PWM signals represents an amplitude of a drive current for the electric load, the control circuit also configured to generate a logic driving command of a half-bridge of the full-bridge stage a logic value of which corresponds to a sign of the drive current by combining the first and second PWM signals, the control circuit also configured to generate a third PWM driving signal of the other half-bridge of the full-bridge stage a duty-cycle of which corresponds to the amplitude of the drive current, the control circuit comprising:
 a first logic gate configured to be input with the first and second PWM signals and generate therefrom a first logic signal; 
 a logic sampling circuit configured to generate the logic driving command by sampling one of the first and second PWM signals based upon active switching edges of the first logic signal; and 
 a second logic gate configured to be input with the logic signal and the logic driving command and generate therefrom the third PWM driving signal. 
 
     
     
       8. The control circuit of  claim 7 , wherein the logic sampling circuit comprises a D-type flip-flop clocked by the active switching edges of the first logic signal. 
     
     
       9. The control circuit of  claim 7 , wherein the electric load comprises a voice coil motor. 
     
     
       10. A method of making control circuit for a full-bridge stage to drive an electric load, the method comprising:
 configuring PWM generation circuitry to generate a first PWM signal and a second PWM signal so that a difference between duty-cycles of the first and second PWM signals represents an amplitude of a drive current for the electric load; 
 configuring a logic XOR gate to be input with the first and second PWM signals and generate therefrom a logic XOR signal; 
 configuring a logic sampling circuit to generate a logic driving command of a half-bridge of the full-bridge stage, a logic value of which corresponds to a sign of the drive current, by sampling one of the first and second PWM signals based upon active switching edges of the logic XOR signal; and 
 configuring a second XOR gate to be input with the logic XOR signal and the logic driving command and generate therefrom a third PWM driving signal of the other half-bridge of the full-bridge stage, a duty-cycle of which corresponds to the amplitude of the drive current. 
 
     
     
       11. The method of  claim 10 , wherein the logic sampling circuit comprises a D-type flip-flop clocked by the active switching edges of the logic signal. 
     
     
       12. The method of  claim 10 , wherein the electric load comprises a voice coil motor.